In general, a page-wide array printer comprises a substrate transport path and a print head or array of print heads extending the full width of the substrate transport path. Such an arrangement allows the entire width of a substrate to be printed simultaneously.
It can be desirable to clean print heads from time to time. For example, debris may accumulate on the surface of a print head, and may adversely affect the operation of the print head.
Ink may dry on the surface of or within a print head, and may clog or block one or more nozzles of the print head. This is not usually a problem if a print head is printing continuously. However, if an image being printed has areas of white space (that is, ink-free areas), this may result in some or all of the nozzles of a print head not firing for several (for example, two, three, five or even more) seconds. In those periods when it is not operational, a nozzle may become blocked with dried ink.
In conventional scanning printers, in which the print head or heads move across a substrate perpendicular to the direction of travel of the substrate, these problems are alleviated by regularly moving the print heads to a cleaning station comprising a spittoon, for example at the end of each printing pass, or after each page has been printed. At the spittoon, the print heads may spit ink in order to keep the nozzles moist and prevent ink drying thereon.